Electric valve circuits



Dec.- 28, 1943. E. E. MOYER 2,337,918

ELECTRIC VALVE CIRCUITS Filed 001. 5, 1941 Invent or: Elmo E. Meyer,

b jva/wy i y His Attorney.

Patented Dec. 28, 1943 ELECTRIC VALVE cm-currs Elmo E. Meyer, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application October 3, 1941, Serial No. 413,418

7 Claims.

My invention relates to electric valve circuits and more particularly to electric circuits employin electric valve means of the type comprising ionizable mediums, such as a gas or a vapor.

In many applications employing electric valve apparatus, it is frequently desirable to operate two electric valve means in parallel in order to meet the current requirements of a particular load condition. In accordance with the teachings of my invention described hereinafter, I provide a new and improved arrangement for assuring that the electric valve means which are intended to operate in parallel are rendered conducting simultaneously and conduct equal amounts of current.

It is an object of my invention to provide new and improved electric valve circuits.

It is another object of my invention to provide new and improved control circuits for electric valve translating apparatus.

It is a further object of my invention to provide new and improved control circuits for electric valvetransl'ating apparatus wherein pairs of electric valves are rendered conducting simultaneously and are controlled to conduct equal amounts of current.

Briefly stated, in the illustrated embodiments of my invention I provide control or excitation circuits for electric valve translating apparatus wherein pairs of electric valve means are intended to operate in parallel relationship and are intended to conduct equal amounts of current. In order to obtain this result, it is necessary that the electric valve means of each pair be rendered conducting in substantial simultaneity, and'that the electric valve means conduct current during equal periods of time. More specifically, I provide improved control circuits wherein equalizingmeans are connected between the excitation circuits to accelerate the operation of the excitation circuit associated with the electric valve means of each pair which tends to lag the operation of the other electric valve means of that 'pair. excitation circuits comprise electric discharge devices of the controlled type having a pair of control grids, one of which is energized by a voltage which tends to render the discharge devices conducting at a predetermined time during the cycle of voltage of the associated alternating current circuit and the other control grids of each electric discharge device are crisscrossed or cross-connected to the excitation circuit of the other electric valve means or the pair.

For a better understanding of my invention,

The

reference may be had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims. Fig. 1 represents an embodie ment of my invention as applied to a polyphase rectifying system; and Fig. 2 is a modification of the arrangement shown in Fig. 1.

Referring now to Fig. 1, I have there illustrated my invention as applied to an electric valve translating system, such as a. rectifying system, for

transmitting power between a polyphase alternating current supply circuit l and a direct current load circuit comprising a positive conductor 2 and a negative conductor 3. The translating system also includes an inductive network which may comprise a transformer 4 having a plurality of primary windings 5 and secondary windings 6, l and 8 which are electrically displaced. Connected to each of the secondary windings 6, I and 8 I provide pairs of electricvalve means which are intended to operate in parallel relationship. For the purpose of simplifying the presentation of my invention, only electric valve means 9 and I0 associated with winding 6 are illustrated; and it will be appreciated that other pairs of electric valve means are also connected to windings l and 8. As a current balancing or dividing means, I provide auto-transformers or current dividing reactors ll, l2 and I3 which are connected between windings 6 and 8, respectively, and the associated pairs of electric valve means. Electric valve means 9 and Ill are preferably of the type employing an ionizable medium, such as a gas or a vapor, and each includes an anode 14,- a cathode l5 and a control member'lli. l he control members I6 may be oi the immersion-igniter type having a portion thereof extending into the mercury of the cathode l5 and are constructed of a material such as boron carbide or silicon carbide having an electrical resistivity relatively large compared with that of the associated mercury pool cathode. Arc discharges within the electric valve means 9 and rare initiated by the transmission of a predetermined critical value of current to the control members I6.

I provide excitation circuits l1 and it which are associated with electric valve means 9 and I0, respectively, and which comprise electric discharge devices l9 and 20. Electric discharge devices l9 and 20 may be of the high vacuum type or of the type employing an ionizable medium such a a gas or avapor and each includes an anode 2|, 9. Cathode 22 and control means such as a pair of control grids 23 and 24. The'anodel3 and 20 are connected to be responsive to the anode voltages of electric valve means 9 and M, respectively, and are connected to the anodes l4 thereof through impedance elements such as resistances 25 and 26; If desired, current protective means such as fuses 21 and 28 may also 8 and Ill, respectively, by connecting these control grids to the anodes 2| through resistances 29 and 30. In this manner voltages are impressed on the control means of the discharge devices l9. and 20 tending to render these discharge devices and electric, valve means 9 and I conducting at a predetermined time during each' cycle of voltage device iii in the event electric valve means [0 of winding 6.

As equalizing means and as means for accelcrating the operation of one or the other of the excitation circuits I! or l8 in the event it tends to lag in. its operation in supplying an impulse of current to control member I8 of either electric valve means 9 and I0, I provide means such as conductors 3| and 32, which may include in series relation resistances 3| and 32', respectively. Theequalizing means are connected between the control means of the electric discharge device in one excitation circuit to the other excitation circuit. In the particular embodiment illustrated in Fig. 1, the conductor 3| is connected between control grid 24 of electric discharge device |9 and the cathode 22 of electric discharge device 20 in excitation circuit l8. In like manner, control grid 24 of electric discharge device 20 is connected to the cathode 22 of discharge device IS in excitatiomcircuit IT.

The operation of the embodimentof my inven tion shown in Fig. 1 will be explained by considering the system when it is operating as a polyphase rectifier to transmit unidirectional current to the load circuit including conductors 2 and 3. It will be understood that each pair of electric valve means associated with windings 0-3 conducts current during 120 electrical degree periods, and that each pair of electric valve means conducts current simultaneously. The current is balanced between the pairs of electric valve means by virtue of the current dividing reactors I 3.

Excitation circuits 1 and I8 transmit impulses of current to control members l6 of electric valve means 9 and ill, tending to render these electric valve means conducting simultaneously and causing the electric valve means to conduct equal amounts of current. By virtue of the connection of grids 23 to be responsive to the anode voltages, the electric valve means 9 and H) are-rendered conducting at a predetermined time during the cycle when the current transmitted to the control members It attainsthe value necessary in order to initiate the arc discharges. The resistances 25 and 26 may be proportioned so that electric valve means 9 and I0 are not rendered conducting until the desired time during the cycle of voltage ofcircuit I, in this manner effectin control of the time at which commutation of current is effected from one of the other pairs of electric valve means or from that pair preceding it in the order of phase rotation. It is. of course, intended that thelmpulses of current transmitted to control member it occur si- 2,337,918 cathode circuits of the electric discharge devices multaneously, thereby rendering the electric valve means 3 and I0 conducting at exactly the same instant. However, in some instances one of the electric valve means 9 or It may be rendered conducting at a time preceding the other, and in accordance with my invention the equalizing means connected between the excitation circuits i1 and I8 tends to accelerate the operation of the discharge device of the excitation circuit associated with the electric valve means which tends to lag or follow.

If it be assumed that electric valve means 9 is rendered conducting before the electric valve means It), the conductor 32 and resistance 32 serve to increase the voltage difference between the control grid 24 and cathode 22 of electric discharge device 20, thereby accelerating the operation of the electric discharge device 20. In like manner, the conductor 3| and resistance 3 I serve to accelerate the operation of electric discharge begins to conduct current priorto electric valve means 9. Accordingly, by virtue of this equalizing means the electric valve means 9 and it! are controlled to conduct substantially equal amounts of current.

Fig. 2 represents, a further embodiment of my invention which is similar in many respects to that shown in Fig. 1, and corresponding elements have been assigned like reference numerals. In the arrangement of Fig. 2, I provide a control circuit 34 which impresses on grids 23 of electric discharge devices l9 and 20 a voltage which tends to render the electric discharge devices l9 and 20 conducting simultaneously. The control circuit 34 may be energized from the alternating current supply circuit I and may include a transformer 35 having a plurality of primary windings 36 and secondary windings 37, 38 and 39. Winding 31 is connected to grids 23 of electric discharge devices l9 and 2!) and windings 38 and 39 are, of course, intended to be connected to the excitation circuits for the pairs of electric valvemeans (not shown) associated with windings I and 8. A suitable source of negative unidirectional biasing potential, such as a battery 40, may be connected in the manner illustrated. The control circuit 34 may also include a phase shiftingdevice 4| to control the phase of the voltage impressed on grids 23 of electric discharge devices l9 and 20 and thereby control an electrical condition, such as the voltage of the direct current circuit.

The embodiment of my invention illustrated in Fig. 2 operates in substantially the same way as that explained above in connectionwith the arrangement shown in Fig. 1. The electric discharge devices I9 and 20 are rendered conducting at times determined by the setting of the phase shifter 4| and the excitation circuits l1 and I8 supply impulses of unidirectiona1 current to the control member I6, thereby tending to render the electric valve means 9 and I0 conducting at the same instant during each cycle of voltage of the supply circuit. The equalizing means comprising conductors 3| and 32 and resistances 3| and 32' also serve to accelerate the operation of the excitation circuit associated with the electric valve means which tends to lag.

The above described embodiment of my invention not-only serves to balance the current conducted by the electric valve means of each pair but also serves an additional protective function in that it tends to lessen the probability of subjecting one electric valve means to the total load current where the load current is of a magnitude which requires that the current be divided between a pair of electric valve means.

While I have shown and described my invention as applied to particular systems of connections apparatus connected between the circuits comprising an inductive network including a plurality of windings, a plurality of pairs of electric valve means each associated with a different one of said windings, said electric valve means each comprising an anode, a cathode and a control member, current balancing means connected between the respective electric valve means of each pair and the associated winding, a plurality of electric discharge devices each connected to the control member of a different one of said. electric valve means for rendering the associated electric valve means conducting, said electric discharge devices each comprising an anode, a cathode and a pair of control grids, means for impressing on one of the control grids of each of the discharge devices associated with each pair of electric valve means voltages tending to render said electric discharge devices conducting at predetermined times during a cycle of voltage of said supply circuit, and means for connecting the cathode of the discharge device associated with one electric valve means in each pair to the other control grid of the discharge device associated with the other electric valve means.

2. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between the circuits comprising an inductive network including a plurality of windings, a plurality of pairs of electric valve means each associated with a different one of said windings, said electric valve means each comprising an anode, a cathode and a control member, current balancing means connected between the respective electric valve means of each pair and the associated winding, a plurality of electric discharge devices each connected to the control member of a different one of said electric valve means for rendering the associated electric valve means conducting, said electric discharge devices each comprising an anode, a cathode and a pair of control grids, means for impressing on one of the control grids of each of the discharge devices associated with each pair of electric valve means voltages tending to render said electric discharge devices conducting at predetermined times during a cycle of voltage of said supply circuit, and means for connecting the other control grids of the electric discharge devices associated with one pair of electric valve means to be responsive to the potential of the cathode of the other electric discharge device of the associated pair and for causing the electric valve means to conduct substantially the same amount of current. a.

3. In combination, an alternating current circuit, a load circuit, electric translating apparatus connecting the circuits and comprising an inductive network including a plurality of windings, a

plurality of pairs of electric valve means each associated with a different one of said windings, said electric valve means each comprising an anode, a cathode and a control member, current balancing means connected between the respective electric valve means of each pair and the associated winding,'a plurality of excitation circuits each connected to the control member of a difierent one of said electric valve means and each including an electric discharge device comprising an anode, a cathode and a pair of control grids, means for impressing on one of the grids of each of the discharge devices of each associated pair voltages which tend to render the pair of electric discharge devices and the associated pair of electric valve means conducting simultaneously, andmeans connected between the other control grid of one discharge device associated with one electric valve means to the excitation circuit connected to the other electric valve means of that pair to equalize the currents transmitted by said electric valve means.

4; In combination, an alternating current circuit, a load circuit, electric translating apparatus connecting the circuits and comprising an inductive network including a plurality of windings, a plurality of pairs of electric valve means each associated with a different one of said wind ings, said electric valve means each comprisingan anode, a cathode and a control member, current, balancing means connected between the respective electric valve means of each pair and the associated winding, a plurality of excitation circuits each connected to the control member of a difierent one of said electric valve means and each including an electric discharge device comprising an anode, a cathode and a pair of control grids, means for impressing on one of the grids of each of the discharg devices of each assoclated pair voltages which tend to render the pair of electric discharge devices and the associated pair of electric valve means conducting simultaneously, and means for increasing the potential applied to the control member of one electric valve means in the event the other electric valve means of that pair is rendered conducting at a time other than at the same time comprising cross-connections between the cathodes and the other control grids of the electric discharge devices.

connected between the circuits comprising an inductive' network including a plurality of windings, a plurality of pairs of electric valve means each associated with a difierent one of said wind= ings, said electric valve means'each comprising an anode, a cathode and a control member, current balancing means connected between the re spective electric valve means of each pair and the associated winding, a plurality of excitation cir cuits connected to the control members of said electric valve means and each including an electrlc discharge device comprising an anode, a cathode and control means, means for impressing on the control means of said electric discharge devices voltages tending to render the discharge devices associated with each pair of electric valve means conducting simultaneously, and means cross-connected between the excitation circuits and the control means of the electric discharge devices associated with each pair to control the potential of the control means.

6. In combination, an alternating current circuit, a load circuit, electric translating apparatus connected between the circuits comprising an inductive network including a plurality of windings, a plurality of pairs of electric valve means each associated with a different one of said windings, said electric valve means each comprising an anode, a cathode and a control member, current balancing means connected between the respective electric valve means of each pair and the associated winding, a plurality of excitation circuits each associated with a difierent one of said electric valve means and each including an electric discharge device having an anode, a cathode and control means for controlling the conductivity thereof, the anode-cathode circuits of said electric discharge devices being connected between the anode and the control member of the associated electric valve means, means for energizing said control means of ach electric discharge device in response to the anode voltage of the associated electric valve means, and equalizing means connected between the control means of one discharge device and the cathode of the other discharge device associated with each pair of electric valve means.

'7. In combination, an alternating current circuit, a load circuit, electric translating apparatus connected between the circuits comprising an inductive network including a plurality of windings, a plurality of pairs of electric valve means each associated with a different one of said windings, said electric valve means each comprising an anode, a'cathode and a control member, current balancing means connected be tween the respective electric valve means of each pair and the associated winding, a plurality of excitation circuits each associated with a different one of saiclelectric valve means and each including an electric discharge device having an anode, a cathode and a pair of control grids, the anode cathode circuits of said electric discharge devices being connected between the anode and the control member of the associated electric valve means, means energized from said alternating current circuit for impressing in-phase voltages on one of the grids oi the discharge devices as sociated with each pair of electric valve means, and equalizing means cross-connected between the other control grids and the excitation circuits of each associated pair of electric valve means to render said pair of electric valve means conducting simultaneously.

' ELMO E. MOYER. 

